1. Field of the Invention
This invention relates to a winding machine for a rotor of, for example, an electric motor and a method of fabricating the rotor.
2. Description of the Related Art
A winding machine having a flyer for winding a wire on the core of a rotor is disclosed in, for example, Japanese Unexamined Patent Publication No. 8-33291. In the winding machine of this type, as understood from schematic perspective view FIG. 6 showing a flyer 105 and a rotor 102, flyer 105 is rotated around a flyer rotation axis AXf orthogonal to a rotor axis AXs, while at the same time supplying a wire 106 from a nozzle arranged at the forward end of flyer 105, and wire 106 is guided to a plurality of predetermined slots (not shown) formed on the rotor core of rotor by a guide unit 104 so that the wire is wound along a path including the slots.
FIG. 7 is a side view schematically showing the state in which rotor 102 having a commutator 124 is set in a conventional winding machine, and in which flyer rotation axis AXf and a circular track T at the forward end of the flyer are also shown. In a conventional winding machine, as shown in FIG. 7, the position of flyer rotation axis AXf coincides with a center line CL along an axial length L of a rotor core 123.
FIG. 8 is a sectional plan view taken in the plane containing rotor axis AXs of the essential parts of a conventional winding machine with rotor 102 having a commutator 124 set in position. A shaft 121a on the side having commutator 124 is chucked by a chuck unit 131 of a holding unit of the winding machine thereby fixing rotor 102 to the winding machine. Chuck unit 131 has the function of not only fixing rotor 102, but also covering commutator 124, and has a cylindrical contour with a tapered forward end to avoid interference with the wire at the time of the winding operation (in this specification, the “chuck unit” is also referred to as the “commutator cover”). The winding machine shown in FIG. 8 has, though not shown, a pair of flyers symmetric about rotor axis AXs. The wires (not shown) supplied from the flyer pair are guided by two guide units 104 arranged on the two sides of core 123 of the rotor to predetermined slots (not shown) of core 123.
In view of the fact that the wire is also wound on the end surfaces of the core, the core and the commutator are arranged at a predetermined interval with each other. Generally, a winding operation is easy for a rotor with a wide interval. However, in the case where the interval of the rotor is narrow, the wire may be damaged by interference with the commutator cover. In the case where the interval is narrower, the gaps designated by reference numerals 110 between commutator cover 131 and guide units 104 in FIG. 8 are further reduced, thereby posing the problem that the wire is stagnated in gaps 110 and cannot be guided to the slots.